Endoscopic and laparoscopic surgical instruments are often preferred over traditional open surgical devices since a smaller incision tends to reduce the post-operative recovery time and complications. The use of laparoscopic and endoscopic surgical procedures has been relatively popular and has provided additional incentive to develop the procedures further. In laparoscopic procedures, surgery is performed in the interior of the abdomen through a small incision. Similarly, in endoscopic procedures, surgery is performed in any hollow viscus of the body through narrow endoscopic tubes inserted through small entrance wounds in the skin.
Laparoscopic and endoscopic procedures generally require that the surgical region be insufflated. Accordingly, any instrumentation inserted into the body must be sealed to ensure that gases do not enter or exit the body through the incision. Moreover, laparoscopic and endoscopic procedures often require the surgeon to act on organs, tissues and/or vessels far removed from the incision. Thus, instruments used in such procedures are typically long and narrow while being functionally controllable from the proximal end of the instrument.
Significant development has gone into a range of endoscopic surgical instruments that are suitable for precise placement of a distal end effector at a desired surgical site through a cannula of a trocar. These distal end effectors engage the tissue in a number of ways to achieve a diagnostic or therapeutic effect (e.g., endocutter, grasper, cutter, staplers, clip applier, access device, drug/gene therapy delivery device, and energy device using ultrasound, RF, laser, etc.).
Known surgical staplers include an end effector that simultaneously makes a longitudinal incision in tissue and applies lines of staples on opposing sides of the incision. The end effector includes a pair of cooperating jaw members that, if the instrument is intended for endoscopic or laparoscopic applications, are capable of passing through a cannula passageway. One of the jaw members receives a staple cartridge having at least two laterally spaced rows of staples. The other jaw member defines an anvil having staple-forming pockets aligned with the rows of staples in the cartridge. The instrument includes a plurality of reciprocating wedges which, when driven distally, pass through openings in the staple cartridge and engage drivers supporting the staples to effect the firing of the staples toward the anvil.
One known problem with using surgical staplers in this fashion has been the formation of air leaks in stapled lung tissue. The leaks can occur in the cut line, and/or in the staple holes themselves. Frequently, the diseased lung tissue is thin and friable and can tear at the staples as the lungs re-inflate. These air leaks can be persistent and can extend the hospital stay for a patient by weeks. To alleviate these leakage problems, surgeons reinforce the staple line by applying a buttress or pledget material to the desired stapling site and stapling through the buttress material. The buttress material provides reinforcement to the friable tissue. The tissue is compressed against the staple holes resulting in increased pneumostasis. This reduces the chances of tissue tearing at the staple line, and reduces staple pullout in friable tissue.
These reinforcement materials are typically releasably mounted onto the jaw members of a surgical stapling device such that upon firing, the reinforcement material is stapled to the lung tissue. Optimally the lung tissue is “sandwiched” between two layers of this reinforcement material. Alternately, buttress materials can be used in a number of other surgical procedures such as but not limited to: an ovarian hysterectomy, a gastric bypass, an anastomosis of intestinal tissue, or any other procedure that requires reinforcement of a staple line or increased hemostasis in tissue.
Releasably attaching the buttress material to the jaw members of the surgical stapling device presents a special challenge. The buttress material must be fastened securely to the jaws of the surgical stapling device so that it will not fall off during normal operation, yet the material must be easily released from the surgical stapling device after the staples are fired. A variety of adhesive and mechanical attachment means are known. Both adhesive and mechanical attachment means are discussed below, and both have their deficiencies.
One example of a device which attaches a buttress material to a linear cutter with an adhesive is described in U.S. Pat. No. 5,441,193 by Gravener et al. This device attaches buttress materials to a surgical instrument with a biocompatible cyanoacrylate adhesive. The adhesive bonding is applied along the edge portions of the buttress material and dashed lines of perforations are placed within the buttress material (adjacent to the glue line) so that the unglued central portion of the buttress material can be torn from the glued edge portions. However, the portions of the buttress material having the adhesive applied thereto are not releasable from the device. As a consequence, removing the buttress from the instrument (after firing) can be especially difficult, as all of the material between the perforations must be torn simultaneously to release the surgical stapling device from tissue. An improved approach to adhesively engaged buttress material was subsequently disclosed in U.S. Pat. No. 6,656,193 to Grant that included both mechanical alignment features in combination with a reliable adhesive with beneficial characteristics for attachment and detachment.
It is also known to employ various mechanical attachments of the buttress material to the surgical stapling and severing instrument. Many methods of mechanical attachment exist, and a common one is the placement of a sleeve over the clamping members of the surgical stapling device. The sleeves can be formed from flexible fabric such as buttress material, or can contain a releasable strip of buttress material attached to a different fabric. Many of these sleeves are described in U.S. Pat. Nos. 5,503,638 and 5,549,628 by Cooper et al, in U.S. Pat. No. 5,702,409 by Rayburn et al., in U.S. Pat. No. 5,810,855 by Rayburn et al., and in U.S. Pat. No. 5,964,774 by McKean et al.
While sleeves can effectively be used to attach the buttress material to the end effector of the surgical stapling device, sleeves can cause other complications during surgery. For example, if the sleeve is formed from a solid sleeve of buttress material, such as in U.S. Pat. Nos. 5,902,312 and 5,769,892, firing the surgical stapling device staples the buttress and tissue and severs the buttress sleeve and tissue between the staple lines. This action leaves the portions of tissue (on either side of the cut line) attached together by a sheet of buttress material. This requires the surgeon to go in and sever the cut sleeve of the buttress to separate the severed tissue, and remove any unwanted portion of the buttress material.
It is also known to incorporate frangible features that are a compromise between a strong hold to prevent inadvertent detachment and unduly high force to detach after stapling. For instance, in U.S. Pat. Nos. 5,542,594, 5,908,427, and 5,964,774 to McKean et al., buttress material is pinned onto end effector surfaces. In U.S. Pat. Nos. 5,702,409 and 5,810,855 to Rayburn et al., porous polytetrafluoroethylene (PTFE) tubes fit over each jaw with each having a tear away flat face. As a compromise, it would be desirable that retention force be higher prior to stapling and reduced after stapling.
Consequently, a significant need exists for an improved surgical stapling and severing instrument that may reliability position buttress material on each side of tissue that is to be stapled and severed with the buttress material thereafter easily deployed from the instrument.